Improved measurement techniques for high-power transistor modeling

Measurement for modeling of the high-power transistors is difficult due to its high-power and low-impedance characteristics. In this paper, novel methods and devices were designed and applied to achieve precise measurements of the high-power transistors. Fixtures capable of withstanding high voltage and current were designed to replace traditional radio frequency (RF) probes for higher power capacity. To reduce the impact of capacitive and inductive components of traditional bias tees on the rising/falling edge, two wideband 90° hybrid couplers that were connected back-to-back were designed for pulsed measurements. The measurement system of stable S-parameters with the Vector Network Analyzer (VNA) was reported, which could protect the devices and laboratory equipment from damage of self-oscillation. Application of several innovative approaches enabled accurate I-V characteristic and S-parameters measurements of high-power transistors in DC or pulsed mode. Experimental results of a 30 W gallium nitride high-electron-mobility transistor verified the validity.